Polylepis frontinensis T.Boza & M.Kessler, 2022

Boza Espinoza, Tatiana Erika & Kessler, Michael, 2022, A monograph of the genus Polylepis (Rosaceae), PhytoKeys 203, pp. 1-274 : 1

9. Polylepis frontinensis T.Boza & M.Kessler sp. nov.

Figs 31 , 32

Diagnosis.

This species differs from Polylepis quadrijuga Bitter (1911) in having obovate leaflets with shorter villous hairs and a lower number of stamens and from P. sericea Wedd. (1857) by obovate leaflets (versus elliptic leaflets), serrate leaflet margins (versus entire) and longer styles.

Type.

Colombia. Antioqui : Urrao, Páramo Frontino, 06°30'N, 76°07'W, 3400 m, 5 Sep 2000, J.A. Perez & N. Parra 1477 (holotype: MEDEL!)

Description.

Trees 4-8 m tall. Leaves only slightly congested at the ends of the branches, imparipinnate with 3-4(5) pairs or lateral leaflets, obtrullate in outline, (2.5-)3.3-5.2 × (1.8-)2.3-3.5 cm; rachises villous, point of leaflet attachment with a tuft of long, straight hairs, slightly resinous, stipular sheaths acute at the apex with spurs, densely sericeous on the outer surface; leaflets obovate in outline, second pair from the terminal leaflet the largest, one of this pair (1.1-)1.4-2.0 × 0.4-0.8 cm; margin serrate with 5-6 teeth, coriaceous, apically slightly emarginate, basally unequally cordate; upper leaf surfaces glabrous with few trichomes in the mid-vein depression; lower surfaces densely villous with hairs 1.4-1.8 mm. Inflorescences pendant, 6.3-10.6 cm long, bearing 7-15 flowers; floral bracts 4.5-5.4 mm long, narrowly triangular, sparsely villous on the outer surface; rachises sparsely villous. Flowers 7.5-8.2 mm diam.; sepals 3-4, ovate, densely villous outside; stamens 9-11; styles fimbriate, 2.8-3.2 mm long. Fruits turbinate, with variable number of spines, densely villous; 3.3-3.6 × 4.7-5.6 cm including spines. Diploid.

Distribution, habitat, and ecology.

Polylepis frontinensis occurs in north-western Colombia in the Páramo Frontino, also called Páramo del Sol (Fig. 41 ). It grows at the upper limit of humid montane cloud forest at 2900-3680 m elevation. Polylepis frontinesis forms 4.9% (132.74 ha) of the total area of Polylepis forest identify for Colombia ( Fadiño and Caro 2009, as P. quadrijuga ). It occurs in small populations in a matrix of mixed forest dominated by species of the genera Escallonia , Hesperomeles , Myrsine and Weinmannia ( Rangel-Ch and Arellano 2010). Some populations occur along streams, where they are mixed with Gynoxys baccharoides ( Rangel-Ch and Arellano 2010).

Etymology.

This species is named after the Páramo Frontino to which its distribution appears to be restricted.

Conservation status.

Polylepis frontinensis is restricted to the upper humid montane cloud forest limit in the Páramo Frontino. Its estimated extent of occurrence (EOO) and area of occupancy (AOO) are 24 km2. The area of distribution of the species is largely unprotected, except for the private Reserva Colibrí del Sol which only includes a few hundred individuals of this species (M. Kessler, pers. obs.). In addition, there is evidence of clearance of Polylepis forests elsewhere in the páramo ( Rangel-Ch and Arellano 2010). We assess the species as Critically Endangered (B2ac, C2a).

Notes.

The populations of Polylepis from Páramo Frontino have previously been identified either as P. quadrijuga or P. sericea (e.g., Rangel-Ch and Arellano 2010, Fajardo-Gutierrez et al. 2018). Indeed, P. frontinensis resembles P. quadrijuga in having 3-4 lateral leaflet pairs and long inflorescences with numerous flowers. However, it has obovate leaflets with villous hairs 1.4-1.8 mm long, whereas P. quadrijuga has elliptic leaflets with tomentose hairs 0.7-0.9 mm long. Additionally, P. frontinensis is morphologically similar to P. lanuginosa and P. sericea with which it shares similar lower leaflet surface hair density and the number of stamens (13-15). The most obvious differences between P. frontinensis and these species is leaflet shape, with P. frontinensis having obovate leaflets, whereas the other two species have elliptic leaflets. Furthermore, P. frontinensis has longer styles (2.8-3.2 mm) than P. lanuginosa and P. sericea (1.9-2.5 mm). In P. lanuginosa , the hairs on the lower leaflet surfaces are yellowish and lanate, whereas in P. frontinensis they are whitish and villous. The three species can also be distinguished by the leaflet margins, with P. frontinensis having serrate margins, P. lanuginosa crenate margins and P. sericea entire margins.

Considering the morphological intermediacy of P. frontinensis with P. quadrijuga and P. sericea , we hypothesize that this species might be of hybridogenic origin between members of section Sericeae subsection Sericeae and section Polylepis Reticulatae .

Specimens examined.

Colombia. Antioquia: Urrao, Vereda El Chuscal, sector Alto de las campanas, hacia La Laguna Campanas, 06°27'46"N, 076°07'37"W, 3830 m, 20 June 2013, Alvarez 84 (HUA!, MO!); Páramo del Sol, Sector Alto del Burro, 3600 m, 17 April 2011, Alzate 4168 (HUA!); Chical, Reserva ProAves “Colibrí del Sol" Páramo frontino, 06°26'22"N, 076°05'47"W, 3300 m, 04 February 2015, Kessler 14772; 14773; 14774; 14775; 14776; 14777 (Z!); Paramo de Frontino , Llano Grande , 3460 m, 06 January 1984, Londoño 51 (HUA!,MEDEL); Paramo de Frontino , 06°30'N, 076°07'W, 3400 m, 05 September 2000, Perez & Parra 1477 (MEDEL); Paramo de Frontino , 3450 m, 22 September 1994, Renteria 10555 (HUA!); Paramo de Frontino , Zona situada entre el 15 y la Esperanza, 2980-3680 m, 18 May 1985, Renteria 4038 (HUA!); Paramo de Frontino , sitio Llano grande, 06°27'24"N, 076°07'22"W, 3380 m, 10 September 1986, Roldán 315 (COL!, MO!, HUA!); Páramo frontino. Camino de Puente Largo al cerro Cuchilla de Frontino , 06°30'N, 076°07'W, 3600-3800 m, 19 July 1995, Sánchez 2244 (COL!, MEDEL); Paramo de Frontino. Camino entre Puente Largo y Llano Grande, 06°30'N, 076°07'W, 3550-3600 m, 20 July 1995, Sánchez et al. 2289 (MEDEL); Páramo El Sol, Vereda La Encarnacion , 06°29'12"N, 076°06'33"W, 3518 m, 24 May 2014, Sarrazola 699 (HUA!). Páramo Frontino, near Llano Grande , 3450 m, 26 October 1976, Boeke 235 (MEDEL, MO!) .

Figures

Figure 31. Polylepis frontinensis T. Boza & M. Kessler A flowers B flowering branch C upper leaflet surface D habit. Scale bars: 5 mm (A); 2 cm (B); 1 cm (C). Photographs by M. J. Sanin.

Figure 32. Polylepis frontinensis T. Boza & M. Kessler A flowering branch B stipular sheaths C upper leaf surface D lower leaf surface E fruits (A Alvarez 84 B-E Kessler 14777). Scale bars: 5 cm (A); 3 cm (C, D); 3 mm (E). Photographs by T. E. Boza E.

Figure 41. Geographical distribution of the species of subsection Polylepis Sericeae Sericeae.